1. Field of the Invention
The present invention relates to devices used for transfer of data over digital communication networks.
2. Prior Art
Data communication devices are conventionally known, through the use of which, both speech and data can be transmitted over digital communication lines. When such a conventional data communication device is employed, in order to establish a voice link with a remote station and then initiate transmission of digital data, the following operations are carried out by the individual operating the device:
a) the telephone number of the remote station is entered and a connection and voice link therewith is established;
b) disconnect after confirming that data is to be transferred; and
c) reentering the telephone number of the communication destination or activating a re-dial function, and then initiating transfer of data after a data link has been established with the remote station.
On the other hand, facsimile devices having a conversation circuit and a modem (modulator and demodulator) are conventionally known, through the use of which, both speech and picture data can be transmitted. When an individual transmits picture data by using such a conventional facsimile device, the individual calls the desired remote station and communicates with the individual who operates the remote station, after which the individual in the local station depresses a communication start button, whereby the telephone line is automatically released from the conversation circuit and connected with the modem, and then the picture data is transmitted to the remote station via the telephone line.
With the above described types of conventional data transfer device, when it is desired to transmit data while a spoken conversation between a local and remote station, before the start button for transfer of data is pressed, the number of the destination station must be manually reentered or a re-dial function must be activated. For this reason, the number of manual steps is increased, as well as is the chance for operator error. Additionally, the spoken conversation is interrupted during transmission of data. Furthermore, when the station first called desires to initiate transfer of data to the remote station, the telephone number of the remote station must be looked up and manually entered, or an autodialer must be activated.